1. Field of Invention
This invention relates to water dispersible, free flowing solid softening compositions for textiles and textile fibers, and a process for their manufacture.
2. Description of the Related Art
The tendency for laundered textile fibers to acquire rigidity and static charges is most pronounced when the laundry product is a synthetic detergent. Stiffness of the fibers and static charges combine to impart a palpable harshness to the textile. Articles of clothing, bed linens and the like, possessing such harshness, are irritating to the skin and uncomfortable to wear. In addition, they tend to retain wrinkles and attract dirt and dust. These undesirable consequences of laundering have been overcome by the use of quaternary ammonium compounds, among others. Quaternary ammonium compounds are currently widely used to impart softness and pliability to the textile and to diminish static charges. Quaternary compound softeners may be a component of the laundry detergent, may be added separately to the wash water at some point in the laundry cycle, or dispensed in the dryer.
The utility of quaternary salts of bis(alkylamidoalkyl)amine, especially those derived from fatty acids, as softeners for textile fibers in laundry applications, and a method for their preparation, are set forth in U.S. Pat. No. 3,492,324. This patent teaches that the quaternary compounds are obtained as semi-solids or solids, which are admixed with appropriate quantities of water to form pastes. These pastes, which are "pourable", may then further be admixed with water to form dispersions suitable for incorporation onto textiles or textile fibers for the purpose of softening them.
Aqueous pastes are by their nature incapable of being incorporated into powdered laundry products, without deleteriously affecting the free flowing characteristics of such products. Further, aqueous pastes or dispersions suffer from handling, storing, packaging, and shipping disadvantages.
Problems inherent in the use of such aqueous systems include: storage instability due to changes in temperature, which result in the separation of the quaternary compound from the water; loss of water due to evaporation, which alters the concentration of softener in the mixture and results in non-uniform application of the softener. In order for formulators to use the paste itself, it must be removed from the container and dispersed with sufficient water to obtain a softening dispersion. Bulk dispensing of a paste under these circumstances is physically difficult, and results in losses of paste itself and inaccurate dispensing of softening material.
An alternative to the paste form of bis(alkylamidoalkyl)amine-derived quaternary fabric softening compounds is as an aqueous dispersion. Such aqueous dispersions suffer from the inherent problems of aqueous pastes, and in addition, require the use of bulkier rigid metal or plastic shipping containers, which increases the cost of storage and transportation.
It is also known in the art that the dispersibility in water of such quaternary fabric softening compounds, and the stability of aqueous dispersions thereof, may be enhanced by the addition of fatty alcohols, e.g., U.S. Pat. No. 4,102,795.
The literature does not reveal the use of bis(alkylamidoalkyl)amine-derived quaternary fabric softeners in particulate or powder form. The physical properties of these quaternary compounds e.g.; high viscosity in the molten state; melting range, on the order of 100.degree. C; and a decomposition temperature of about 120.degree. C; are not conducive to preparation of particulates or powders. We have, however, discovered a convenient method for the preparation of bis(alkylamidoethyl)amine-derived quaternary fabric softening compounds in the form of particulates or powders.